The present invention is directed to driver apparatuses employed in inter-device communications signaling, and especially to such driver apparatuses employed in high speed communication systems.
In high speed communications systems such as, by way of example and not by way of limitation, data communication systems, speed of signal handling is less of a problem when effecting intra-chip communications than when carrying out inter-chip communications. Inter-chip high speed communication is generally limited by the performance of chip communication termination circuits, such as driver and receiver circuits at the interface of communicating chips. Speed of a driver circuit is generally indicated by the speed at which the driver circuit can effect signal transitions. Signal transitions—such as from a high signal level to a low signal level, or from a low signal level to a high signal level—are used in digital data communications to convey information. The speed at which the necessary information-indicating signal transitions can be carried out directly affects the speed of the communication system.
Inherent driver circuit limitations often limit speed of communication that can be achieved by a system. This is so even though intra-chip communications are easily carried out at desired high speeds. Chip-to-chip communication (i.e., inter-chip communication) often presents bottlenecks in certain aspects of design of a system, such as communications with motherboards, optical transmission links, intelligent network hubs, routers and other system components. If one of the inter-chip interfaces experiences slow communications, then the entire system is slowed.
Earlier attempts at increasing operational speed of driver apparatuses has involved, for example, sensing a signal downstream, such as at the driver output, and using that sensing to determine application of a boosting signal to an upstream driver locale, such as within the driver output circuitry. Such an approach to increasing speed of a driver apparatus is disclosed in U.S. Pat. No. 6,628,150 to Carvajal et al. for “System and Method to Speed-Up Operation of a Driver”, issued Sep. 30, 2003. The problem with such an approach is that application of the remedial boosting signal necessarily occurs too late to aid in speeding the transition of the output signal that is sensed.
There is a need for an apparatus and method for handling interdevice signaling between a sending device and a receiving device that improves signaling speed between the sending device and the receiving device.